Binary Interaction Parameters Research Articles

Influence of excipients on solubility of oxcarbazepine: Modeling and prediction based on thermodynamic models

In this work, the solubility of oxcarbazepine in polymers (PEG 6000, PEG 20,000, PVP K25, and PVP K30) and their aqueous solutions was investigated by experimental measurement and thermodynamic modeling. Firstly, the solubility of oxcarbazepine in water and polymers was modeled and the corresponding binary interaction parameters (oxcarbazepine + water and oxcarbazepine + polymer) were determined based on the experimental phase equilibrium data. Furthermore, the solubility of oxcarbazepine in the polymer aqueous solution (the mass ratios of polymers in water were 2 %, 4 %, and 6 %) was predicted by the solid-liquid equilibrium (SLE) coupled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). It was observed that the predicted results agreed well with the experimental data, and the average relative deviation (ARD) was <7 %. In this study, the solubility of oxcarbazepine in polymer aqueous solution was successfully predicted through the SLE coupled with the PC-SAFT, which was expected to provide theoretical guidance for the selection of pharmaceutical excipients and the rational design of preparations.

Calculations of mean ionic activity coefficients of copper and manganese salts in aqueous solutions

Accurately predicting the activity coefficients of copper and manganese salts in aqueous solutions is crucial for treating industrial wastewater, and it is of practical interest to calculate the activity coefficients of heavy metals in aqueous solutions using the Equation of State because of its high flexibility and wide range of applicability. This work conducts a modeling study on the mean ionic activity coefficients of copper and manganese salts in aqueous solutions. The thermodynamic framework used in this work is an electrolyte version of the Cubic Plus Association Equation of State (e-CPA). The model's ion-water binary interaction parameters are obtained by regressing the osmotic coefficients and mean ionic activity coefficients in aqueous solutions. The modeling results indicate that the electrolyte Equation of State can satisfactorily correlate the water activity, osmotic coefficients, and mean ionic activity coefficients of copper and manganese salts in aqueous solutions over a wide range of salt concentrations. Among all the systems at 298.15 K, the biggest average relative deviation between calculated and experimental values is within 6.7 % and 2.3 % for the mean ionic activity coefficients and water activity, respectively. Furthermore, this work discusses the impact of ion pairs on the phase equilibrium of aqueous systems from a microscopic mechanism perspective and analyzes and discusses the model's adaptability. The model used in this work can accurately predict the activity coefficients of a variety of copper and manganese salts in aqueous solutions over wide concentration ranges and provides an improved interface for improving the calculation accuracy of the model under high concentration or other complex conditions.

Can liquid-liquid equilibria be predicted by the combination of a cubic equation of state and a [formula omitted] model not suitable for liquid-liquid equilibria?

In modern versions of cubic equations of state (EoS), the mixing rules for EoS parameters are derived from an activity coefficient model using either the Huron-Vidal or the Zero Reference Pressure (ZRP) approach. As it is a fact that Wilson's activity coefficient model cannot predict liquid-liquid equilibria (LLE), this article attempts to answer the question: if Wilson's model is coupled with a cubic EoS, is the resulting model capable of predicting LLE?This question is actually becoming increasingly important as recent EoS rely on such a coupling (e.g., the tc-PR EoS). We show that although Wilson's model is mathematically unable to predict instable liquid phases, this is not true for Wilson-EoS models (i.e., EoS incorporating Wilson's model). However, it is also shown that the capacity of Wilson-EoS to predict LLE depends not only on the approach chosen (Huron-Vidal or ZRP) but also on mixture characteristics (such as the ratio of covolumes, the ratio of critical attractive parameters, the binary interaction parameters etc.).

Vapor-liquid equilibria of the ternary system of methane + n-decane + n-octacosane at high pressures

Alkane mixture phase equilibria is required for a range of industrial applications, most particularly for the petroleum industries. Mixtures containing light and heavy normal alkanes are of even further significance due to their non-ideal thermodynamic behavior. In this work, for the first time, the ternary system of C1 + C10 + C28 was investigated experimentally to obtain bubble point pressures at various concentrations and temperatures ranging from 373 up to 445 K. The synthetic method of phase equilibrium measurements was utilized, which is known to have high accuracy. The resulting bubble points for the mixtures ranged in pressure from about 3 MPa up to 6 MPa. The data indicated that methane concentrations had the greatest impact, not only on the magnitude of the bubble point pressure, but also on the slope of its temperature trend. The relative concentrations of n-decane and n-octacosane had far less impact on the bubble point curves. The results were also modelled using the Peng–Robinson equation of state, and it was found that this equation has the capability to predict the data with an AARD% of 5.1 %. When temperature-independent binary interaction parameters were optimized to the data, the AARD% reduced to 2.4 %. Although the components vary greatly in size, perhaps the success of the Peng–Robinson equation of state for this mixture could be attributed to the fact that it was developed for hydrocarbon mixtures, and so, a reason for its popularity in the petroleum industries, alongside its simplicity and ease of use.

Speed of Sound Measurements of R-1130(E) and an Azeotropic Blend of R-1336mzz(Z)/1130(E)

Sound speed data measured using a dual-path pulse-echo instrument are reported for pure trans-1,2-dichloroethene (R-1130(E)) and an azeotropic blend of cis-1,1,1,4,4,4-hexafluorobutene (R-1336mzz(Z)) and R-1130(E) with a composition of 74.8 mass % R-1336mzz(Z) with the balance being R-1130(E). The azeotropic blend of R-1336mzz(Z)/1130(E) is classified as R-514A in ANSI/ASHRAE standard 34. Liquid phase speed of sound data are reported from just above the saturation pressure of pure R-1130(E) or the bubble point pressure of R-514A to a maximum pressure of 26.7 MPa. The relative combined expanded uncertainty in the speed of sound varies from 0.032 % to 0.148 % with the greatest deviations occurring at the lowest sound speeds. At present, no reference Helmholtz-energy-explicit equation of state (EOS) is available for R-1130(E). Therefore, the reported data for pure R-1130(E) are compared to an extended corresponding states (ECS) model. Deviations between the pure R-1130(E) sound speed data and the ECS model were found to be consistently negative ranging between − 4.1 % and − 3.5 %. The R-514A data are compared to a multifluid model inclusive of the established reference Helmholtz-energy-explicit EOS for R-1336mzz(Z) and ECS model for R-1130(E) with estimated binary interaction parameters. Deviations between the experimental speed of sound data and the multifluid model were also found to be consistently negative. However, deviations from the multifluid model were found to be as great as − 17.1 %. The large deviations from the ECS model and multifluid model underscore the need for a robust Helmholtz-energy-explicit EOS for R-1130(E).

Enhanced Solubility and Miscibility of CO2-Oil Mixture in the Presence of Propane under Reservoir Conditions to Improve Recovery Efficiency

The existence of propane (C3H8) in a CO2-oil mixture has great potential for increasing CO2 solubility and decreasing minimum miscibility pressure (MMP). In this study, the enhanced solubility, reduced viscosity, and lowered MMP of CO2-saturated crude oil in the presence of various amounts of C3H8 have been systematically examined at the reservoir conditions. Experimentally, a piston-equipped pressure/volume/temperature (PVT) cell is first validated by accurately reproducing the bubble-point pressures of the pure component of C3H8 at temperatures of 30, 40, and 50 °C with both continuous and stepwise depressurization methods. The validated cell is well utilized to measure the saturation pressures of the CO2-C3H8-oil systems by identifying the turning point on a P-V diagram at a given temperature. Accordingly, the gas solubilities of a CO2, C3H8, and CO2-C3H8 mixture in crude oil at pressures up to 1600 psi and a temperature range of 25–50 °C are measured. In addition, the viscosity of gas-saturated crude oil in a single liquid phase is measured using an in-line viscometer, where the pressure is maintained to be higher than its saturation pressure. Theoretically, a modified Peng–Robinson equation of state (PR EOS) is utilized as the primary thermodynamic model in this work. The crude oil is characterized as both a single and multiple pseudo-component(s). An exponential distribution function, together with a logarithm-type lumping method, is applied to characterize the crude oil. Two linear binary interaction parameters (BIP) correlations have been developed for CO2-oil binaries and C3H8-oil binaries to accurately reproduce the measured saturation pressures. Moreover, the MMPs of the CO2-oil mixture in the presence and absence of C3H8 have been determined with the assistance of the tie-line method. It has been found that the developed mathematical model can accurately calculate the saturation pressures of C3H8 and/or CO2-oil systems with an absolute average relative deviation (AARD) of 2.39% for 12 feed experiments. Compared to CO2, it is demonstrated that C3H8 is more soluble in the crude oil at the given pressure and temperature. The viscosity of gas-saturated crude oil can decrease from 9.50 cP to 1.89 cP and the averaged MMP from 1490 psi to 1160 psi at 50 °C with the addition of an average 16.02 mol% C3H8 in the CO2-oil mixture.

Kinetic modeling of palmitic acid hydrodeoxygenation incorporating phase-equilibria predictions from the GC-PC-SAFT equation of state

In this work, we investigated the phase equilibria and the kinetics of palmitic acid hydrodeoxygenation over Pt/C to produce liquid hydrocarbons as drop-in biofuels. To describe the reaction mixture in detail, the binary interaction parameters of water/hydrogen, water/palmitic acid, water/n-hexadecane, and water/hexadecan-1-ol were estimated for a group contribution model based on the PC-SAFT equation of state using experimental solubility data taken from literature. Kinetic modeling using a power law model based on concentrations, a power law model based on fugacities, and a coupled VLE/power-law model were conducted to evaluate the effects of considering the non-ideality and the phase equilibria of the system. Under the operational conditions studied, the power law model based on concentrations was deemed more suitable to describe the process since it provided a faster implementation and similar outcomes compared to the fugacity-based and the VLE coupled models.

Fluid Phase Equilibria Carbon Dioxide + Decane + Hexadecane Ternary System

The interest in understanding reservoir fluids' phase behavior is to increase hydrocarbon production without any flow assurance issues. Due to its opacity, the evident complexity of determining phase equilibrium data revolves around the thermodynamic modeling of model systems. The article presents experimental phase equilibrium data and thermodynamic modeling for the CO2 + decane + hexadecane ternary system at 283.15, 298.15, and 323.15 K and pressures up to 20 MPa. The transitions observed during this study were liquid-liquid (LL), vapor-liquid (VL), and vapor-liquid-liquid (VLL). The Peng-Robinson equation of state was used to model this ternary system for various compositions. The temperature-dependent binary interaction parameters (kij) for the CO2 + n-alkane mixtures were adjusted to the experimental data. Additionally, a binary interaction parameter for the n-C16H34/n-C10H22 pair, independent of temperature, was obtained through the critical volume of the components. The results reveal complex behaviors as the mixture's composition of hexadecane progressively increases. Adding this longer-chain linear hydrocarbon influences the phase behavior, leading to the emergence of liquid-liquid transitions and barotropic inversion in the system. This study contributes valuable data on model systems representing crude oil, highlighting complex behaviors in ternary systems with high carbon dioxide content.

High-pressure phase equilibrium for carbon dioxide solubility with biofuels: Experimental and thermodynamic insights in 2,5-dimethylfuran and methyl levulinate

The solubility of carbon dioxide in two solvents, 2,5-dimethylfuran and methyl levulinate, were measured to high pressure, up to 9.1 MPa, at three different temperatures (283.15, 303.15 and 323.15) K. The new data were measured using both the isothermal synthetic technique and the variable volume synthetic method. Two methods were utilised to provide a level of data validation. The uncertainties in the measured data were critically estimated. The experimental phase equilibrium data were modeled using the Peng-Robinson equation of state and the Wong-Sandler mixing rule with a single set of binary interaction parameters for each system. The data indicated that the solubility of carbon dioxide in both 2,5-dimethylfuran and methyl levulinate at high pressures was relatively low, suggesting a low capacity of these biofuels to dissolve carbon dioxide at high pressure.

Experimental and thermodynamic study of amyl acetate, amyl acetoacetate, and isoamyl acetoacetate in CO2 solvent

Acetate ester compounds find widespread use in various applications such as surface coatings, ink formulations, pharmaceuticals, and adhesives. It is essential to investigate the phase transition behavior of amyl acetate, amyl acetoacetate, and isoamyl acetoacetate in high-pressure supercritical CO2 (SC-CO2). The vapor-liquid equilibria (VLE) of the SC-CO2 + amyl acetate, SC-CO2 + amyl acetoacetate, and SC-CO2 + isoamyl acetoacetate systems were examined at different temperatures (313.2 ≤ T ≤ 393.2 K) and pressures (1.67 ≤ P ≤ 20.76 MPa). The solubility curve of these systems shows Type-I phase behavior, and the critical points of these binary mixtures were observed between the critical properties of the pure components involved in the systems. The solubility of amyl acetate, amyl acetoacetate, and isoamyl acetoacetate in the SC-CO2 + amyl acetate, SC-CO2 + amyl acetoacetate, and SC-CO2 + isoamyl acetoacetate systems increases with increasing temperature at constant pressure. The two-parameter model of Peng-Robinson equation of state along with a mixing rule, accurately correlated the phase transition behavior and critical mixtures curves for all three systems. The binary interaction parameters (BIPs) were adjusted, and the minimum root mean square deviation percentage was identified for all three systems. The calculated error% was found to be within reasonable limits, with values of 4.95 %, 3.93 %, and 4.18 % for SC-CO2 + amyl acetate, SC-CO2 + amyl acetoacetate, and SC-CO2 + isoamyl acetoacetate systems, respectively. Furthermore, the interaction parameters for the SC-CO2 + amyl acetoacetate mixture was found to be temperature-dependent, and the tested linear regression correlation coefficient for the BIPs parameters of (kij) and (ηij) are 0.98533 and 0.99083, respectively. This is the first research study on the phase behavior of acetate ester compounds in SC-CO2 solvents, and the results have a significant impact on industries at different operating conditions.

CO2 sorption of elastomer poly(ionic liquid)s with imidazolium cations having different alkyl chains: Structure-morphology-property relationships and thermodynamic modelling by the PC-SAFT equation of state

In this work related to Carbon Capture and Storage (CCS), the CO2 sorption capacities of a new family of elastomer poly(ionic liquid)s (PILs) with imidazolium cations having different alkyl chains were studied. These PILs were synthesized by chemical modification of polyepichlorohydrin (polyECH) obtained by living anionic polymerization. PolyECH was quaternized with different 1-alkylimidazoles (alkyl = methyl, n-butyl, and n-hexyl) and followed by anion exchange to obtain three PILs: PIL-Me, PIL-nBu, and PIL-nHex. They were analyzed by NMR (1H, 13C, 2D 1H/13C HSQC, APT 13C) and characterized by SEC, DSC, calorimetry, rheology, and XRD SAXS/WAXS. The influence of the alkyl chain on the PIL CO2 sorption was studied with a magnetic suspension balance (MSB) at 35 °C and CO2 pressures varying from 1 to 10 bar. The best results were obtained with PIL having methyl chains (9.60 mg CO2/g PIL at 1.1 bar and 159.28 mg CO2/g PIL at 10.0 bar at 35 °C). Finally, the CO2 sorption properties of these PILs were modeled with the PC-SAFT equation of state (EoS). The pure-component parameters were obtained from model regression of the PILs densities calculated by the Bondi's and Van Krevelen's methods. The binary interaction parameters of the systems CO2/PIL were optimized with average absolute deviations (AAD) lower than 6.3 % for the three PILs. The PC-SAFT modelling of their sorption properties opens interesting prospects for modelling the CO2 sorption process for CCS facilities.

Efficient separation of alcohol ester via extractive distillation and pressure swing distillation based on molecular interaction mechanism analysis

N-amyl alcohol, n-amyl formate, n-propanol and n-propyl formate are all organic solvents with important industrial application value. In industrial production, related alcohol ester azeotropic systems are often generated. Therefore, it is necessary to study the refining process of these substances. The work designed purification processes for two different azeotropic systems of alcohol esters via extractive distillation and pressure swing distillation methods. The required binary interaction parameters were obtained through vapor–liquid equilibrium experiments. Based on experimental data, a suitable entrainer was determined through different methods of analysis. The processes were optimized with the economic cost as the objective. In addition, it evaluated and analyzed different processes from multiple perspectives. This work explores the purification process of alcohol ester systems, providing theoretical guidance for achieving efficient separation of alcohol ester systems.

Separation of 2-ethoxyethanol from wastewater by four esters: Correlation of LLE thermodynamic modeling, influence of molecular structure, and investigation of component interactions

To prevent the wastewater containing 2-ethoxyethanol (2EE) from causing environmental pollution and economic waste, liquid–liquid extraction was used to recover 2-ethoxyethanol from wastewater in this study. The liquid–liquid equilibrium behavior of water + 2-ethoxyethanol + four solvents (propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate) was investigated at 303.2 K and atmospheric pressure. The distribution coefficient (D) and separation factor (S) were used to compare and discuss the extraction efficiency of each system. The results indicated that all esters could effectively separate 2-ethoxyethanol from water. Among them, isobutyl acetate exhibited the highest values for D and S, demonstrating its superior separation capability. The experimental data were correlated with the thermodynamic model and interaction parameters were obtained. These parameters were verified using the GUI-MATLAB tool, and all four systems passed validation, confirming the reliability of the obtained binary interaction parameters. Furthermore, the root mean square deviation (RMSD) was used to assess the deviation between the experimental and regression values. The RMSD values for the NRTL and UNIQUAC models were 0.008 and 0.007, respectively. The interactions between 2-ethoxyethanol and water or esters were explored using σ-Profile, and it was found that esters with a branched chain structure provided better extraction. To explain the properties of the extractants microscopically, the interaction energies between 2-ethoxyethanol molecules and water or ester molecules, as well as the non-bonding energies of 2-ethoxyethanol in different media, were calculated.

Vapor-liquid equilibrium data for the binary system isopropanol+water at 60 kPa and 80 kPa

In this work, experimental Vapor-Liquid Equilibrium (VLE) data for the Isopropanol + Water system under vacuum conditions at 60 kPa and at 80 kPa, for which no experimental evidences have been found in the literature, are reported. The experimental investigation of the isobaric equilibrium has been carried out by GASP at the Process Thermodynamics laboratory (PT lab) of Politecnico di Milano by employing an all-glass dynamic recirculation still. The collected experimental data, together with those already available in the literature at other conditions, have been used for the evaluation of the thermodynamic model that best fits the data. Four different models have been considered and their performances have been checked through the calculation of the Absolute Average Deviation (AAD%). The lowest AAD% has been found for the UNIFAC model only for isobaric data, not for the isothermal points. The regression tool available in Aspen Plus® V14 has been used to fit the binary interaction parameters of the NRTL activity model.

Determination and intermolecular interaction analysis of the liquid–liquid equilibrium of water, acrylic acid, and different solvents at 303.2 K and 101.3 kPa

To explore the effective treatment of acrylic acid wastewater, liquid–liquid equilibrium (LLE) data for water + acrylic acid + {n-propyl acetate, n-butyl acetate, n-heptanol, and methyl isopropyl ketone} at 303.2 K and 101.3 kPa were measured respectively. The distribution coefficients (D) and separation factors (S) were used to assess the extraction effectiveness of the four solvents, and the results of the comparative data showed that the D values of the four solvents for acrylic acid ranged from 1.6 to 4.4, and the S values were in the order of n-butyl acetate > n-propyl acetate > MIPK > n-heptanol. The experimental data were fitted by NRTL and UNIQUAC models to obtain the binary interaction parameters, and the obtained above parameters were proved reliable by the mixing surface analysis method of Gibbs energy topology. The root mean square deviation (RMSD) of both models did not exceed 0.0051 and 0.0077, respectively. In addition, σ-profiles analyzed the differences in extraction effects in terms of interactions and interaction energies, and the analyses showed that the theoretical calculations are in agreement with the experimental results.

Vapor‐liquid interfacial properties of binary mixtures from molecular simulation and density gradient theory

AbstractProperties of the vapor‐liquid interface of 16 binary mixtures were studied using molecular dynamics simulations and density gradient theory in combination with the PCP‐SAFT equation of state. All binary combinations of the heavy‐boiling components (cyclohexane, toluene, acetone, and carbon tetrachloride) with the light‐boiling components (methane, carbon dioxide, hydrogen chloride, and nitrogen) were investigated at 0.7 times the critical temperature of the heavy‐boiling component in the whole composition range. Data on the surface tension, the enrichment, the relative adsorption, and the interfacial thickness, as well as for the vapor‐liquid equilibrium and Henry's law constant are reported. The binary interaction parameters were fitted to experimental data in a consistent way for all systems and both methods. Overall, the results from both methods agree well for all investigated properties. The interfacial properties of the different studied systems differ strongly. We show that these differences are directly related to the underlying phase equilibrium behavior.

Energy-saving design of azeotropic distillation for the separation of methanol–methyl methacrylate azeotrope from industrial effluent

For the purpose of separating the binary methanol–methyl methacrylate (MMA) azeotrope in light boiling residues and preventing MMA polymerization from acetone cyanohydrin process, low pressure heterogeneous azeotropic distillation (HAD) with process intensification was adopted. The binary interaction parameters of the azeotrope were obtained by correlating and regressing the experimental data of isobaric vapor–liquid equilibrium at low pressures (75, 50 and 26 kPa for methanol-MMA and 26 kPa for cyclohexane-MMA). The residue curve map at 26 kPa was plotted under the UNIQUAC model, and the optimal parameters of its conventional process were achieved through sequential iterative optimization procedure. The purity of MMA and methanol was 99.99 wt% and 99.90 wt%, respectively. Subsequently, in order to further reduce costs and energy consumption, dividing wall column (ADWC), heat pump distillation (HP-AD), and heat pump assisted azeotropic dividing wall column (HP-ADWC), three technical approaches were explored and compared. Total annual cost (TAC), total energy consumption (TEC), and CO2 emissions were used as evaluation indicators. Among them, ADWC reduced its annual capital investment by 14.48 % through special structural design. HP-AD effectively reduced TEC by 27.30 %. HP-ADWC combined the advantages of both, effectively reducing costs and saving energy (12.88 % in TAC). At present, the purity and energy saving of the product meet industrial expectations, providing valuable insights for enhanced methanol-MMA azeotrope recovery from industrial effluent.

Experimental and model-based approach to evaluate solvent effects on the solubility of the pharmaceutical artemisinin

The separation and purification of plant-based Active Pharmaceutical Ingredients (API) from extracts is a crucial part in pharmaceutical process development. For the purification of the antimalarial drug component artemisinin (ARTE) from an Artemisia anna L. toluene extract, antisolvent crystallization is considered. Solubilities of ARTE in binary solvent mixtures of toluene and two potential antisolvents, n-heptane and ethanol, were determined at temperatures from 278.15 K to 313.15 K. The experimental work was supported by the application of various models, utilizing varying amounts of experimental input data. The goal was the identification of models that are able to predict solubilities in binary solvent mixtures sufficiently accurate and, thus, can help to reduce the experimental effort for future solvent screenings. In this study, we applied the PC-SAFT model both with and without fitting the binary interaction parameter kij between ARTE and the respective solvent, as well as the empirical Jouyban-Acree model. From the experiments, n-heptane demonstrated to be a promising antisolvent, while ethanol acted more as a cosolvent. All models tested were capable of distinguishing between effective and ineffective antisolvents. The purely predictive PC-SAFT model applied with kij = 0 exhibited the largest deviation from the experimental data. This was followed by the PC-SAFT model including fitted kij values, based on at least four experimental data points. The Jouyban-Acree model fitted the data most accurately. Its parametrization required a minimum of ten experimental data points.

Techno-economic analysis of AMP/PZ solvent for CO2 capture in a biomass CHP plant: towards net negative emissions

Compared to conventional monoethanolamine (MEA), alternative solvents are expected to substantially contribute to reduce the energy demand of post-combustion CO2 capture from flue gases. This study presents a comprehensive techno-economic analysis of a 27 wt% 2-amino-2-methyl-1-propanol (AMP) + 13 wt% piperazine (PZ) aqueous solution for CO2 capture, compared to a 30 wt% MEA solution. The study addresses the retrofit of a carbon capture unit to a biomass-fired combined heat and power (CHP) plant, effectively making it a bioenergy with a carbon capture and storage (BECCS) system. The treated flue gas has a flow rate of 23 tons/hour (t/h) with 11.54 vol% CO2 and a 90% capture rate is aimed for. Aspen Plus V14 was employed for process simulations. Initially, binary interaction parameters for AMP/PZ, AMP/H2O, and PZ/H2O are regressed using vapor-liquid equilibrium (VLE) data, which were retrieved from literature along with reaction kinetics. Validation of parameters from available experimental literature yields an average absolute relative deviation (AARD) of only 5.9%. Afterwards, a process simulation model is developed and validated against experimental data from a reference pilot plant, using a similar AMP/PZ blend, resulting in 5% AARD. Next, a sensitivity analysis optimizes operating conditions, including solvent rate, absorber/stripper packing heights, and stripper pressure, based on regeneration energy impact. Optimized results, compared to MEA, reveal that AMP/PZ reduces the energy consumption from 3.61 to 2.86 GJ/tCO2. The retrofitting of the capture unit onto the selected CHP plant is examined through the development of a dedicated model. Two control strategies are compared to address energy unavailability for supplying the capture unit. The analysis spans 4 months, selected to account for seasonal variations. At nominal capacity, CO2 emissions, rendered negative by biomass combustion and CO2 capture, reach a maximum of −3.4 tCO2/h compared to 0.36 tCO2/h before retrofitting. Depending on the control strategy and CHP plant operating point, the Specific Primary Energy Consumption for CO2 Avoided (SPECCA) ranges from 4.91 MJ/kgCO2 to 1.76 MJ/kgCO2. Finally, an economic comparison based on systematic methodology reveals a 7.87% reduction in capture cost favoring the AMP/PZ blend. Together, these findings highlight AMP/PZ as a highly favorable alternative solvent.

Simulation and optimization of crude glycerol refining process as a co-product of biodiesel

Glycerol is an essential chemical raw material widely used in industries such as food, pharmaceuticals, cosmetics, tobacco, and textiles. With the increasing production of biodiesel, a considerable amount of crude glycerol co-product is generated. Purification of crude glycerol by separating it from biodiesel co-products can lead to the production of high-purity glycerol, thus enabling the synthesis of high-value-added chemicals to reduce the production cost of biodiesel. This paper proposes a new glycerol purification process based on the acidification of potassium oleate soap using sulphuric acid. The composition of crude glycerol is complex. The presence of salts can affect the binary interaction parameters of glycerol and water. The ion forms resulting from the ionization of potassium fatty acid soaps are not available in the database and require important data to be provided through physical property estimation. Additionally, the dissociation of sulphuric acid is involved in the system. These issues make it challenging to propose a complete process based on the characteristics of crude glycerol. In this study, the vapor–liquid equilibrium data of the glycerol-water system containing potassium sulphate under reduced pressure were experimentally determined, and the binary interaction parameters of the glycerol-water system were regressed and used in the subsequent process simulation. The entire process of crude glycerol refining from biodiesel co-products was simulated and optimized using Aspen Plus software, proposing an optimized complete refining process for crude glycerol and designing a crude glycerol refining process with a production scale of 100,000 tons per year. The potassium oleate soap is first acidified with sulphuric acid, then removed by centrifugation, with the resulting lower layer entering the distillation process. We compared two different distillation processes and identified the more optimal separation sequence. Glycerol products with a mass concentration of 99.2% were obtained, with glycerol and methanol yields of 98.83% and 99.79%, respectively. Based on the above research, energy integration and optimization of the process were further investigated through pinch analysis. Overall, energy savings of 7.192 Gcal/h were achieved, resulting in a reduction in energy consumption of 40.65%. This paper proposes a new purification scheme for crude glycerol and an energy integration scheme to reduce the purification cost of high-purity glycerol. This is significant for the rational utilization of crude glycerol, a co-product of biodiesel.